[Top][All Lists]
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
[Bug-gnubg] GNU Backgammon on backgames
From: |
Øystein O Johansen |
Subject: |
[Bug-gnubg] GNU Backgammon on backgames |
Date: |
Fri, 9 Aug 2002 13:25:03 +0200 |
http://www.bgsnowie.com/backgammon/articles.dhtml?id=56
I can see at Snowie's web site that Johannes Leverman talks nice about
Snowie's 4 backgame improvements to Snowie 3. I could not resist. I entered
these positions into GNU Backgammon, just to see how our little neural net
rates these positions.
The first position Johannes shows is this one:
GNU Backgammon Position ID: YBYScDfYtg0HAA
Match ID : cIkUAAAAAAAA
+24-23-22-21-20-19------18-17-16-15-14-13-+ O: player1
| O | | O O X | 0 points
| O | | O X |
| | | X |
| | | |
| | | |
| |BAR| |v (Cube: 1)
| | | |
| | | |
| O O | | |
| O O O X X X | | X X X | Rolled 15
| O O O X X X | | X X X O O | 0 points
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: player2
O has a very strong backgame and X is not strong enough to double. Snowie 3
gets this wrong. Snowie 4 gets this right. GNU Backgammon also gets this
right.
GNU Backgammon:
Win W(g) W(bg) L(g) L(bg) Equity (cubeful)
static: 0.579 0.423 0.109 0.008 0.000 (+0.682 (+1.000))
1 ply: 0.575 0.434 0.120 0.006 0.000 (+0.696 (+1.000))
2 ply: 0.524 0.381 0.122 0.008 0.000 (+0.543 (+0.779))
No double : +0.779
Double, pass : +1.000 (+0.221)
Double, take : +0.762 (-0.017)
Correct cube action: No double, take
Of course I also showed this position to JellyFish. JellyFish says
double/drop and a cubeless equity of +0.840 which agrees a lot with Snowie
3.
The second position Johannes shows in this article, is this:
GNU Backgammon Position ID: cLeDASTgc3CAGQ
Match ID : cAkFAAAAAAAA
+24-23-22-21-20-19------18-17-16-15-14-13-+ O: player1
| X X O O | | O O X | 0 points
| X X O O | | O O X |
| O O | | O X |
| | | |
| | | |
| |BAR| |v (Cube: 1)
| X | | |
| X | | |
| X | | X |
| X | | X O | Rolled 21
| O O X | | X O | 0 points
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: player2
He is here trying to demonstrate how Snowie 4 makes backgame strategies, by
keeping the backgame plan.
Johannes and Snowie 4 agrees that 6/5 6/4 is the best move, while Snowie 3
says 23/22 23/21 since this move avoids the backgame. GNU Backgammon also
get this right at 2-ply and plays 6/5 6/4. The funny thing is JellyFish. At
level 5 (0-ply) it says: 6/3*. It does not even consider 23/22 23/21 as a
candidate. At level 5 6/5 6/4 is on fifth place. Reevaluating at level 7,
it still says 6/3*, but now 6/5 6/4 ranks as number 2, with a cl equity
difference of only 0.02.
GNU Backgammon:
1. Cubeful 2-ply 6/5 6/4 Eq.: -0.815
0.369 0.059 0.000 - 0.631 0.306 0.024
2. Cubeful 2-ply 13/11 6/5 Eq.: -0.848 ( -0.033)
0.350 0.066 0.001 - 0.650 0.290 0.021
3. Cubeful 2-ply 6/3* Eq.: -0.858 ( -0.043)
0.341 0.064 0.001 - 0.659 0.274 0.018
4. Cubeful 2-ply 23/22 23/21 Eq.: -0.883 ( -0.068)
0.309 0.059 0.001 - 0.691 0.217 0.008
The last position, Johannes tries to demonstrate anti-backgame strategies.
GNU Backgammon Position ID: qHNwABvY3QYDIA
Match ID : cAkaAAAAAAAA
+24-23-22-21-20-19------18-17-16-15-14-13-+ O: player1
| X O O O | | O X | 0 points
| O | | O X |
| O | | O |
| | | |
| | | |
| |BAR| |v (Cube: 1)
| | | |
| | | |
| X X | | O |
| O O X X X | | X X O | Rolled 46
| O O X X X | | X X O | 0 points
+-1--2--3--4--5--6-------7--8--9-10-11-12-+ X: player2
He writes that hitting is a blunder, and Snowie 3 hits but Snowie 4 does
not hit. Unfortunately GNU Backgammon hits as well does.
1. Cubeful 2-ply 24/20* 13/7 Eq.: +0.920
0.616 0.368 0.043 - 0.384 0.035 0.001
2. Cubeful 2-ply 24/20*/14 Eq.: +0.912 ( -0.008)
0.622 0.350 0.038 - 0.378 0.032 0.001
3. Cubeful 2-ply 24/14 Eq.: +0.866 ( -0.054)
0.661 0.254 0.017 - 0.339 0.033 0.001
The rollout really shows this is a blunder.
1. Rollout 24/14 Eq.: +0.809
0.632 0.229 0.011 - 0.368 0.053 0.001 CL +0.450 CF +0.809
[0.002 0.002 0.000 - 0.002 0.001 0.000 CL 0.006 CF +0.019]
Truncated cubeful rollout (depth 15) with var.redn.
648 games, seed 1148792576 using Mersenne Twister
Play and cube: 0-ply cubeful [expert]
2. Rollout 24/20*/14 Eq.: +0.691 ( -0.117)
0.553 0.299 0.022 - 0.447 0.056 0.001 CL +0.370 CF +0.691
[0.002 0.002 0.001 - 0.002 0.001 0.000 CL 0.007 CF +0.020]
3. Rollout 24/20* 13/7 Eq.: +0.689 ( -0.119)
0.547 0.309 0.027 - 0.453 0.058 0.001 CL +0.371 CF +0.689
[0.002 0.002 0.001 - 0.002 0.001 0.000 CL 0.007 CF +0.023]
JellyFish play 24/14 (without the hit) as well even at 0-ply. But the
hitting play 24/20*/14 is only 0.004 cl equity points behind. Shame on GNU
Backgammon in this position.
Based on these three positions, which of course is not enough material to
make a general statement, I would rank the backgame abilities of the bots
in this order:
1. Snowie 4
2. GNU Backgammon
3. JellyFish 3.01
4. Snowie 3
-Øystein
-------------------------------------------------------------------
The information contained in this message may be CONFIDENTIAL and is
intended for the addressee only. Any unauthorised use, dissemination of the
information or copying of this message is prohibited. If you are not the
addressee, please notify the sender immediately by return e-mail and delete
this message.
Thank you.
[Prev in Thread] |
Current Thread |
[Next in Thread] |
- [Bug-gnubg] GNU Backgammon on backgames,
Øystein O Johansen <=